Faker\Provider\ru_RU\Person uses suffix "a" to make a female last name from male, but used symbol was a latin "a" (ASCII #97) and not cyrillic "a" (ASCII #208), so the final last name was "some cyrillic symbols" + "latin a", now female last name forms correctly: cyrillic male last name + cyrillic "a".
Faker\Provider\ru_RU\Person uses suffix "a" to make a female last name from male, but used symbol was a latin "a" (ASCII #97) and not cyrillic "a" (ASCII #208), so the final last name was "some cyrillic symbols" + "latin a", now female last name forms correctly: cyrillic male last name + cyrillic "a".